Interesting, Jeff!! I wouldn't think that, if the cats. are doing their job, there should be anything behind the cats. (fuel) that would allow combustion to occur. The cats. are suppose to burn any unburned fuel before it gets to the tailpipe.

Oops, I see you deleted the cats. That's why this is happening......unburned fuel being ignited in the tailpipe. Kind of cool looking though....like a top fuel dragster. Do you have a way of monitoring your air/fuel ratios? This can be tough on mufflers, depending on how far back into the system the flame is going.

Interesting, Jeff!! I wouldn't think that, if the cats. are doing their job, there should be anything behind the cats. (fuel) that would allow combustion to occur. The cats. are suppose to burn any unburned fuel before it gets to the tailpipe.

Oops, I see you deleted the cats. That's why this is happening......unburned fuel being ignited in the tailpipe. Kind of cool looking though....like a top fuel dragster. Do you have a way of monitoring your air/fuel ratios? This can be tough on mufflers, depending on how far back into the system the flame is going.

I just recently put the cats back on, this was just after porting out intake manifold runners.

Update; its running fine now, I think it just needed to relearn whats going on

Oops, I see you deleted the cats. That's why this is happening......unburned fuel being ignited in the tailpipe. Kind of cool looking though....like a top fuel dragster. Do you have a way of monitoring your air/fuel ratios? This can be tough on mufflers, depending on how far back into the system the flame is going.

for a long while I ran no cats with glasspacks and never gotten flames, if an engine is running the way its supposed to, you will never get flames that far out, it was running extremely rich while trying to relearn its parameters. that is why I had to keep giving it gas so it would stay running....it was cool tho, I admit that